@joseuro - The N64 reader can dump the MN63F81MPN flashram. I have a Pokemon Stadium 2 with the MN63F81 and it dumps using the current 29L1101 save code. The Autodetect does not work as the current reader code does not have the flash id information for the MN chip.
What we found is that there are two groups of flashram chips used in the N64 carts. They're grouped as OLD_FLASH and NEW_FLASH. The OLD_FLASH group is MX_PROTO_A, MX_A and MX_C (29L1100). The MX_PROTO_A and MX_A are in the code base but whether they actually exist in retail carts is unknown (they are Macronix Device ID 00 and 01). The NEW_FLASH group is MX_B_AND_D (29L1101) and MATSUSHITA (MEI) flash (MN63F81).
The cart flashram list that sanni posted earlier is not a definitive list and it is likely that the mid to late 2000 carts could contain any of the flashram chips - 29L1100 (OLD_FLASH), 29L1101 (NEW_FLASH), or MN63F81 (NEW_FLASH). The best way to check is to open up the cart and read the id printed on the chip. Alternatively, you could use the current Autodetect routine which should sort you out if you have a 29L1100 or 29L1101. If you use the Autodetect and get a "Flashram unknown" with the following bytes - 11, 11, 80, 1, 0, 32, 0, F1 then you have the MN63F81 and you should dump it using the 29L1101 mode.
I believe sanni will be updating the reader code with the MEI (MN63F81) flash id so we'll then be able to Autodetect all of the known flashram chips.
Keep in mind that if you're planning to use the save file in an emulator that you might need to saveswap (use saturnu's Saveswap from KRIKzz's forum).